Charles Manson has been in jail for more than four decades. In 1971, he and several of his followers — Tex Watson, Susan Atkins, Patricia Krenwinkel and Leslie Louise Van Houten — were convicted in the era-defining Tate-LaBianca murders that horrified not only Los Angeles, where the murders took place in the summer of 1969, but the entire nation. (Manson was convicted, in essence, as a “conspirator,” as he was not present at the killings, but ordered them to be carried out.)

The ferocity of the murders; the seeming randomness of the violence; and the chilling, bottomless weirdness of the Manson cult itself incised a terrible, indelible black mark on the late 1960s.

But it was during grand jury testimony and at the trial of Manson and his followers — with the trial itself serving as a kind of bleak circus that lasted nine months, from the summer of 1970 to the spring of 1971 — that the nation was able to gauge just how deeply unhinged “the Family” truly was.

Carving x’s in their foreheads? No problem. Shaving their heads to show solidarity with their leader? Done. Blocking entrances to the courthouse, chanting, singing, treating the trial — and, by extension, the murders themselves — like a trip to the amusement park? For the Manson clan, it was all grist for their cheery, death-adoring psychopathy.

After all, if Manson, Krenwinkel and the rest were going to be tried and (quite obviously) convicted of mass murder by the “establishment” and “the pigs” they despised, the least their brothers and sisters in the Family could do was show the world that, in the universe they inhabited, the killers were not truly criminals at all, but instead were iconoclasts. Rebels. Heroes.

Here, LIFE.com presents pictures from late 1969, when Manson and his co-defendants were finally indicted and charged in the Tate-LaBianca murders.

All these years later, the sight of Manson and his dead-eyed acolytes is still ghastly. But as long as pictures like these bear witness, the people whose lives were taken — Sharon Tate; Jay Sebring; Wojciech Frykowski; Abigail Folger; Steven Parent; Leno and Rosemary LaBianca — will remain in sight, and those who slaughtered them will be remembered not (as some would have it) as wayward, misled children, but as men and women who entered the homes of strangers and in a spasm of savagery ended life after life after life.